Roller contact current converter



Jan. 14, 1958 w. GOTRTWALD ROLLER CONTACT CURRENT CONVERTER I5 Sheets-Sheet 1 Filed July 6, 1955 v Jan. 14, 1958 Y wf GQTTWALD 2,820,114

.ROLLER CONTACTl CURRENT CONVERTER Filed July 6, 1953 3 Sheets-Sheet 2 n The ./nven for:

Jm 14; 1953 w, GOTTWALDl p 2,820,114

` ROLLER CONTACT CURRENT CONVERTER Filed July e, 1953 E :s sheets-sheet s United States Patent O ROLLER CONTACT CURRENT CONVERTER Walter Gottwald, Ratingen, near Dusseldorf, Germany, assignor to August Hamilton Schilling, Atherton, Calif.

Application July 6, 1953, Serial No. 366,297

Claims priority, application Germany August 4, 1952 11 Claims. (Cl. 200-19) This invention relates to roller contact current converters and has reference particularly to mechanical roller contact current converters in which the roller contacts roll on circular paths.

With mechanical current converters having roller contacts which roll on circular paths it is desired that the rollers remain along their entire axial widths in contact with the contact path. Also constructions are known which provide two contact paths arranged in parallel, i. e. in superposed relation and in axial aligment, and connected electrically by means of revolving roller contacts. In this case it is absolutely necessary that the rollers connecting both paths have continuous contact with these two paths along the full axial widths of the latter. Since the roller contacts are preferably fixedly journalled their axis of rotation is fixed and therefore it becomes extremely ditiicult to fulll the mentioned requirement.

The present invention has for one of its objects to provide current converters of the type referred to above having special contact rings arranged elastically on the rolling roller contacts, thus enabling these contact rings to take any position that may be required in order to maintain contact with the single contact path straps. Rubber or other elastic material may be used to provide the elastic support for these contact rings. The desired eiect can be realized, for instance, by Supporting the contact ring preferably on a rubber ring or the like arranged in the center, in such manner that the ring is able to assume a position oblique to the axis of rotation of the rollers. However, it is possible to provide several, especially two contact rings which are connected with each other by means of flexible current conductive straps and Wherever each ring is carried by a rubber ring or the like. This type of arrangement is recommendable in particular in such cases where two contact paths are to be connected by means of roller contacts.

The contact rings and the rubber rings can be joined with each other by means of polymerization. Expediently the rubber ring on its part is polymerized to a carrier ring. Tensile stresses are then present in the rubber ring;

' said stresses result from the shrinkage of the rubber on being cooled down after the polymerization process. These tensile stresses influence in undesirable manner the junction formed of rubber and metal and decrease the stability to aging of the rubber. In addition the rubber ring is strained by the rotation of the roller contact in each case on the one side, and the consequence is that, because of the rigidity of the contact ring, on the opposite side tensile stresses arise which are the greater the higher the contact pressure against the contact ring is chosen. Thus, the tensile stresses which arise strive toward loosening the rubber ring from the contact ring.

Therefore, it is a further object of the present invention According to the invention a rubber cushioning arrange- -to provide means for eliminatnig these disadvantages.

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ment designed for carrying the contact rings is put under initial tension or compression. Without further diiculties it can be realized in this manner that said rubber cushioning is not subject to any disadvantageous tensile stresses during operation. This objective can be accomplished in various ways. For instance, the rubber cushioning can by suitable means be put under pressure in the radial direction of the Contact ring. Advantageously, in this case the construction is as follows: The soft rubber cushioning formed by a closed type ring is provided with an interrupted inner ring preferably joined to it by polymerization, consisting of metal or any other suitable material and force-tted onto a carrying body Whose outside diameter is larger by the magnitude of the desired initial stress than the inner diameter of said ring. Another possibility for production of the desired initial tensile or compressed stress is that the rubber cushioning is compressed by suitable means in the direction of the axis of the ring. As rubber practically is not compressible, the applied pressure becomes effective in such manner that an initial stress is produced between said two rings.

To these and other ends, the invention consists in the construction and arrangement of parts that will appear clearly fr0-m the following description when read in conjunction with the accompanying drawings, the novel features being pointed out in the subjoined claims.

In the drawings:

Fig. 1 represents a sectional view of a roller shell according to the invention provided with a shoft rubber cushioned contact ring;

Fig. 2 shows likewise in section a roller shell according to the invention differing from the type shown in Fig. l in that there are provided two rubber cushioned contact rings;

Fig. 3 is a plan view of a contact path fixedly connected with a rubber ring and provided With an inside metal ring consisting of several segments;

Fig. 4 shows the arrangement according to Fig. 3 partly in sectional view and partly in side elevation;

Fig. 5 illustrates another possibility for production of initial compressive stress in the rubber ring;

Fig. 6 illustrates still another embodiment of an ar rangement for production of initial compressive stress in the rubber ring;

Fig. 7 illustrates a further embodiment of such an arrangement, while Fig. 8 finally illustrates diagrammatically and in per spective the principle of construction of a roller contact -current converter adapted for conversion of three-phase A. C. into direct current.

Referring to Fig. 1, a roller shell 1 is carried on an axle 2 by means of the ball bearings 3 and 3. A rubber ring 4 carrying the co-ntact ring 5 is provided on the roller shell 1. The numerals 6 and 7 designate the two contact paths on which the roller electrode 1, 4, and 5 runs when the rectifier is in operation. The contact surface 5 has, by means of the presence of the rubber ring 4, self-aligning capacity within certain limits and independently of the axle 2 to the extent that a good .contact is ensured at all times with the contact paths 6 and 7.

Figure 2 represents a somewhat altered construction. In this case again a roller shell 8 is provided which is rotatably arranged on an axle 9 by means of the ball bearings 10 and 10. In this ligure the roller shell carries two rubber rings 11 and 12 which are encompassed by the contact rings 13 and 14. `The contact rings 13 and 14 are connected current conductively with `each other by means of the flexible conductor straps 15. Thus, during rolling of the arrangement on the contact paths 16 and 17, each contact path 13 and 14 has the possibility of self-alignment independently of the other coutactpath. Thereby, a perfect contactingoccursion uboth paths even if the axle 9 should not be positioned in proper direction or inaccuracies should be present in the contact paths 16 and 17, and thus continuous connection of the .contact paths place properly ineach position of ,the arrangement.

Referring now .to Figure 3, the numeral 18 designates ,a contact path consisting of metal and ,xedlyconnected rvwith the rubber ring 19, for example, by polymerization or vvulcanizationl On its inner side the rubber ring 19 .islikewise connected by `polymerization with a metal ring consisting of -segments 20 `to .23 which are interrupted `by rgapsv24. The gaps `24 make it possible tol force the :entire Varrangement onto a carrying body (for example, then-011er shell 8 .according toFig. 2) having an outer ndiameter llarger than ,the inside diametertof the ring 20 .to 23. Thereby in the rubber ring 19 an initial tension .is .produced which the rubber ,ring `transmits to the `contact path Therefore, tensile stresses which were present inthe rubber will be compensated and can Vno l more act disadvantageously on the connection between rubber and metal. The result is also attained that during vtherun of the rolling arrangement no `or only small -tensile stresses-arise on `theside of the ring lying opposite to the pressure side, and said `small tensile stresses are .notable to .cause loosening of the connection between .contact path 11,8 and rubber ring19. The inside ring 20 ,to, 23 4can be polymerized (vulcanized) in separated conditionfto the rubber ring, `or `it -can b e provided with `gaps after the Apolymerization,process has been carried out.

In Figure 4 the arrangement according .to Fig. `3 is lrepresented fin sectional l,view and partly yin side eleva- ;tion. A In ,the'right half `o f thegure a part 8 receiving the rolling body is indicated.

Other possibilities for production yof initial tensions in athe Krubber :ring L19 :are shown in the Figures 5 .tto 7. '.Invthis texernplied representation `the linitial tensions are produced by compressing the rubber ring 19 in axial direction. lnftheexamplegiven in Fig. 5 this isdone by :means of'two flat lannular disks 2S and 26. It can be recognized without :diitculty .that =the .material that the rrubber ring X19-consists of, since it .is practically incompressible, is sustained with pressure on the one hand :against the contact ring 118 andagainstthe earryingtbody 8 on the othernifthes-rings 25and526 are pressedttogether vin the directiontofthe arrows.

The construction :accordingfto "Figure 6 provides pressure rings having slanted surfaces in place ofrectangular lsurfaces. *The :rubber material is :'put t under t pressure in axial as well as in radial direction, ifi-these rings shown at27 and 28 are'pressed toward/each other. Also, as r:represented in Figure J7, `pressure 4rings 'having langular crossasection'may v-be used advantageously. -With this construction, the rubber ring 19in-sustained only-on its inner side bythe rings 29 and 3l) without exerting any pressure ontothefearrying bofdy. APracticallythe same ecct results from the arrangement of pressure rings =having--s`lanted^surfaces yas shown in'Figure 6, whilethe example given in lFigure 5 provides that the --rubberring `un'der initialy tension bears against the carryingbody 1S.

' 8 fof the drawings Shows infperspective4l the if general arrangement vof/a rollercontact current converter 'adapt Led :to `convert "three-pbase ycurrent 4"into ldirect fcurrent. There are y-providedftwoannular contact-surfaces 45 and 46 which are electrically connected by means `of `the A4 rollers^31-and 4*32. In this Icase-the rollers 31and32 are udesigned in 'thesame -manner -astherollers 1, 4, -5 yin Figure l, and -'forthe-sal;e oiclearness, 4'the details vof the roller'construction --have been omitted. The shafts 't2fof ythecontactfrollersare mounted ont-he oppositefends -of-afdiametrically#extending arm (not shown) -which is "dly connected l'to Ja `drive shaft (not shown) `twhose s is-`indicated-at '33 -33 andwhichfis rotated inithe direct-inn of the arrOWGt-SLbvmeans of `asynchronous Imotor (not represented -in the drawing), Thus the `l Arollers 31 and 32 -rotate 1in .the direction iof Athe .arrows 35 respectively 36 about their own axes and travel on the contact paths 45, 46 'in the direction of the arrows 37 and 38. The contact paths 45 and 46 are formed by the rings 39 and 40. The ring 39 is a closed type metal ring with laid-in segments 41 consisting of insulating ma terial, while the ring 40 consists Aof three metal pieces 42 which are interrupted by pieces 43 made of insulating material. The ,three :phase ,lines R, S, T of a rotary current ,power line are connected t o 4the .metal .pieces 42 of the ring 4t). The tD. ,Cqline =i) 44 leads ,off from the closed ring39. Each of the metal segments 42 extends over .degrees :of @the circle, while `the rinsulating segments 43 extend over 3,0 degrees each. In this example'it is assumed that a rotary currenthaving 50 cycles is to be converted into .direct acurrent. The revolution speed of the synchronous motor and the speed of the rollers 31 and 32 on the contact paths` 45 and 46 about the axis ,fis ithen 3,500 R. 1P. :During :revolution of lthe trollers tthe Segments 42 ,will ghe conducted by means tof the rollers ,31, 32 one :after theother `.with the D. C.collector ring 39, thus supplying current to tthe latterin'one,direction only, and thus establishing athreephasercorninutation operation. There is the radvantage `with ,the tinsulating `pieces -43 `that the switching period can be adjusted:b3/relative `rotation of the ringst39 fand t@ with re remette-eachother.

it @understood tthat froller arrangements Aaccording to Figures .11 tand .2 also :can -`be applied @successfully vwith types ,of construction :of roller `contatzucurrent `converters `which may :differ "frornzthearrangement as ,shown in :Fig-

iure :8 and zthaat :the invention fis not limited to :this preferred example tof application ,-I claim:

1. .Rollen eontacti currentsconverter. `comprisingfincombination, two concentric rings having electrically'conducting arcuate portions at least along -part of v-their peripheries, .at least-,one fof said concentric lrings including an insulating arcuate iportion adjoining -a conducting arcuate portion, V'roller contact means supportedfor Yrolling -on said concentric rings .and -periodically bridging isaid `rings-electrically,ithe support for said roller contact means comprising a-shaft aboutwhose axis the Vroller contact means is rotatable, said `shaft `being bodily rotatable about the axis of Asaid concentric rings,;a rotating support on the shaft for the Vroller contact means, and yielding means disposed between ,and 'rmly lconnected to the roller contact means and to its rotating support fand enabling such contact means `toassume oblique'lpositions to maintain continuous contact with bothconcentric rings despite irregularities in the surfaces o'f said rings, the peripheral yextent of saidinsulating `portion being such that the rollercontact means yatrio time bridges thein- ,sulating portion to make lContact ,simultaneously with the conducting portions bordering the same.

2. A converter according .to ,claim `l, ,wherein said yieldingmeansomprises `aring.of soft .rubber bonded tothe roller Vcontaotfmeans .and to its support. l

3. rA converter taccording to claim ,2, `wherein the rubber Abody is bonded to.the;contact meansandtits-support lpolymerized intermediate layers.

to said contact rings and their support, and exible metallic straps connecting the said contact rings elastically.

6. A converter according to claim 5, wherein said rubber rings are disposed in axially spaced relation and are axially coextensive with the roller contact rings.

7. A converter according to claim 1, including an anti-friction bearing having inner and outer races, the inner races being secured to the shaft, the support for the roller contact means comprising a cylindrical shell secured to and rotating with the outer race of the bearing, said yielding means comprising an annular soft rubber body bonded at its inner surface to the said shell and at its outer surface to the said roller Contact means.

8. A converter according to claim 1, wherein said yielding means comprises an annular body of soft rubber bonded to the contact means and to its support, said rubber body being under a constant pre-compression, whereby the development of tensile stresses in said body is prevented.

9. A converter according to claim 1, wherein said yielding means comprises an annular body of soft rubber bonded to the contact means and to its support, and means for producing a continuous pre-compression in said rubber body for preventing the development of tensile stresses therein.

10. A converter according to claim 1, wherein said yielding means comprises an annular body of soft rubber bonded to the contact means and to its support, said support comprising an anti-friction bearing on the shaft and a cylindrical sleeve composed of segment-shaped parts having gaps therebetween and secured to said bearing, said rubber body having before assembly an inner diameter which is smaller than the outer diameter of its assembled support.

1l. In a rotary contact current converter, the combination'with a pair of concentric, axially spaced circular rings at least one of which has at least one arcuate conducting portion and as many arcuate insulating portions bordering the conducting portion or portions, of a shaft rotatable about the axis of said rings, a roller mounted for rotation on said shaft and including a contact ring bearing on and rolling on said circular rings, and a distortable, elastic, continuous rubber ring between said roller contact ring and the shaft, said rubber ring being under a compressive prestress to cause it to exert a continuous pressure against the inside face of the roller contact ring, the peripheral extent of any insulating portion of the circular ring being such that the roller contact ring at no time bridges the insulating portion to make contact simultaneously with the conducting surfaces bordering the sarne.

References Cited in the file of this patent UNITED STATES PATENTS 547,537 Biddle et al. Oct. 8, 1895 1,404,761 Harris et al. Jan. 31, 1922 1,915,530 Hoisington et al. June 27, 1933 2,133,980 Fowler Oct. 25, 1938 2,268,261 Merkel Dec. 30, 1941 FOREIGN PATENTS 142,578 Great Britain May 13, 1920 

